Some time ago I experienced a bug that caused the brush tool to "paint" over the canvas with white/black graphical boxes that would vary in shapes and sizes. The fix then was to go to preferences -> technology previews -> check off the 2016 gpu mode. This no longer works anymore (I've had this mode on since the first problem and and it remained working until yesterday.) I have also experienced that after a couple of minutes after opening a file the canvas will get laggy. When trying to move the canvas in any way I would experience a significant time delay. The entire service is practically unusable to me right now. This seemingly happened after the auto update yesterday (27.01.2024).